The invention relates to an imager.
Referring to FIG. 1, a typical digital camera 12 uses an imager 18 to electrically capture an optical image 11. To accomplish this, the imager 18 typically includes an array 13 (see FIG. 2) of photon sensing, pixel sensors 20. During an integration interval, each pixel sensor 20 typically measures the intensity of a portion, or pixel, of a representation of the image 11 that is focused (by optics of the camera 12) onto the array 13. At the expiration of the integration interval, each sensor 20 typically indicates (via an analog signal, such as a voltage, for example) an intensity of light of the pixel.
The camera 12 typically processes the indications from the pixel sensors 20 to form a frame of digital data (which digitally represents the captured image) and transfers the frame (via a serial bus 15, for example) to a computer 14 for processing. For video, the camera 12 may capture several optical images and furnish several frames of data, each of which indicates one of the captured images. The computer 14 may then use the frames to recreate the captured video on a display 9.
Referring to FIG. 2, the sensors 20 are typically arranged in rows and columns. In this manner, after the expiration of the integration interval, row 24 and column 22 decoders (of the imager 18) may begin selectively, electrically selecting the sensors 20 to retrieve the indications from the sensors 20.
The decoders 22 and 24 route the selected indications to signal conditioning circuitry 26 which might include, for example, analog-to-digital converters (ADCs) and circuitry to compensate for noise that is introduced by the sensors 20. The signal conditioning circuitry 26 may furnish data signals to an output interface 28 which includes circuitry for interfacing the imager 18 to other circuitry of the camera 12. A control unit 30 may coordinate the above-described activities of the imager 18.
Typically, a multi-color mosaic filter (not shown) covers the array 13 and configures each sensor 20 to sense the intensity of a primary color component of the associated pixel. For example, for the set of red, green and blue primary colors, the filter may cause each sensor 20 to sense either a red, green or blue primary color component of the pixel. Thus, with this arrangement, each sensor 20 only senses one primary color component of the pixel. However, for true color imaging, it may be desirable to obtain the other primary color components of the pixel.
Typically, the missing primary color components are obtained through interpolation. Using interpolation, the missing primary color components for a given pixel are derived by interpolating color components from the nearest pixels (adjacent, for example), or “nearest neighbors.” For example, if a given sensor 20 senses a green component of a pixel, the red primary color component for that pixel may be interpolated from the information provided by neighboring sensors 20 that sense red primary color components. However, the interpolation only provides estimates (and not the actual values) of the missing color components.
Thus, there is a continuing need for an imager that provides actual primary color components of each pixel.